The white smoke rose Monday afternoon from the Congressional Budget Office as the fiscal forecasters published their cost-and-coverage estimates of the GOP health-care reform bill. Awaiting such predictions—and then investing them with supposed clairvoyance—are Beltway rituals. The coverage numbers weren’t great for Republicans, but they shouldn’t allow an outfit that historically underestimates the benefits of market forces to drive policy.

The good news is that CBO estimates that the American Health Care Act would cut...